JPH0312051Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial field of application This invention relates to a device that linearly feeds a driven object along a horizontally arranged guide shaft, and is particularly applicable to linear feeders for optical pickups such as CD (compact disc) players. Regarding a feeding device.

Conventional technology In optical disc players such as CD players,
A linear feeder is provided for reciprocating an optical pickup equipped with an optical system in the radial direction of the disk.

Conventionally, this linear feeding device has been configured as shown in FIG. 5, for example.

As shown in FIG. 5, two guide shafts 1, 1 are arranged in parallel at a predetermined interval, and an optical pickup main body 2 slides on the guide shafts 1, 1 via bearings 3, 3... Possibly installed.
The optical pickup main body 2 has guide shafts 1, 1
The optical head 2a is linearly fed so that the central axis (optical axis) of the optical head 2a moves in the radial direction of the disk D.

The drive system for linearly feeding the optical pickup main body 2 includes a drive motor 4 installed on the base, a worm gear 5 attached to the drive shaft, a worm wheel 6 that meshes with the worm gear 5, and a worm wheel 6 provided coaxially with the worm wheel 6. A small-diameter gear 7, a large-diameter gear 8 that meshes with the small-diameter gear 7, a pinion 9 that is provided coaxially with the large-diameter gear 8, and a rack 10 that meshes with the pinion 9 are arranged on the side of the optical pickup main body 2 in parallel to the feeding direction. It is installed and roughly configured.

For example, the maximum program radius of a disk applied to a CD player is 58 mm, and the portion with a radius of about 16 mm is loaded into the platter attached to the drive shaft of the disk drive motor, and the innermost program radius is set to 23 mm. (58−23)
Information is recorded in the annular part with a width of =35 mm.
The optical pickup main body 2 is configured such that the central axis (optical axis) of its optical head is reciprocated by the aforementioned drive system over a distance of 35 mm in the disk radial direction. The drive motor that drives this drive system is
DC (direct current) motors are generally used.

Problems to be Solved by the Invention The conventional linear feed device using a DC motor as described above has had the following problems.

In conventional drive systems, the driving force of the drive motor is transmitted through a reduction gear system. For this reason, a phenomenon called "backlash" occurs in which the gear meshing error causes a shift when the optical pickup main body is moved forward or backward. Since this deviation is 0.2 mm or more, it has been difficult to precisely perform the tracking servo to align the disk with the track pit row formed with a width of 1.6 μm.

Further, a space is required for arranging a drive system consisting of a drive motor and a reduction gear system, making it difficult to make the overall structure thinner and more compact.

Furthermore, as prior art of such a linear feed motor, Japanese Patent Application Laid-open No. 136865/1982 and Utility Model Application No. 1983-
There is one disclosed in Publication No. 108776. but,
In the technique disclosed in JP-A-55-136865, the output shaft provided on the plunger only penetrates the end cap of the container and protrudes to one side, and does not penetrate or protrude to the other side. The plunger comes into contact with the end cap and its movement forward is restricted. Therefore, there is a drawback that the operating stroke range is narrow. In addition, the plunger and output shaft are made of non-magnetic material rather than magnetic material, and in addition to the electromagnetic drive system that guides, supports, and drives them, bearings must be provided, so the device configuration is This increases the size, which is disadvantageous when trying to make it more compact.

Furthermore, the one disclosed in Japanese Utility Model Application Publication No. 58-108776 is a stepping motor type linear motor, which has the drawback that cogging tends to occur during feeding operation and smooth linear feeding operation cannot be performed.
The drawback is that it cannot be applied to the linear feed drive system of the optical head of an optical disk player such as an LD. Furthermore, since a large number of circumferential groove-shaped step drive gears are provided on the circumferential surface of the cylindrical slider, there is a problem with the durability of the bearing part of the slider during linear feeding, and in this respect, the optical head It is unsuitable for high-speed linear feed drive systems.

This idea was made in consideration of the above points,
The driven body is guided and supported by the guide shaft with a shaft-penetrating support structure, allowing a wide range of linear feed operation strokes, and a resin coating layer is formed on the sliding part to ensure smooth linear feed operation. The present invention aims to make the device structure more compact by having a part of the electromagnetic driver also serve as a bearing of the guide shaft.

Means for Solving the Problems In order to achieve the above objectives, this invention forms a guide shaft, through which the driven body is supported in the linear feed direction via a plurality of bearings, from a magnetic material with high magnetic permeability, At least one bearing is formed by an electromagnetic driver composed of a yoke body, a permanent magnet, and a coil, and a resin coating layer is formed on the sliding surface of either the yoke body or the guide shaft.

Effect According to the above configuration, due to the magnetic force of the permanent magnet,
A magnetic closed loop is formed between the permanent magnet, the yoke body, and the guide shaft, and when a current is passed through the coil in the magnetic field generated between the magnetic closed loops, a force that tends to move the coil is exerted. If this force is applied in the direction along the guide shaft, the electromagnetic driver is moved in the direction along the guide shaft, and the driven object can be linearly fed along the guide shaft. Furthermore, if a current is passed through the coil in the opposite direction to that described above, a force will be applied in the opposite direction. The subject is
Depending on the direction of the current flowing through the coil, the coil is linearly fed in a reciprocating direction along the guide shaft.

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a linear feeding device for an optical pickup main body according to the present invention, and FIG. 2 shows its main parts.

Guide shafts 20 and 21 are arranged in parallel at a predetermined interval. This guide shaft 2
An optical pickup main body 22 is attached to 0 and 21. The optical pickup main body 22 has its head 2
The central axis (optical axis) L of the disk D is linearly fed in a direction along guide shafts 20 and 21 that reciprocate in the radial direction of the disk D.

The optical pickup main body 22 is connected to the guide shaft 2.
0 via bearings 23, 23, and the guide shaft 21 via a bearing 24 and an electromagnetic driver 30.

The guide shaft 21 to which the electromagnetic driver 30 is attached is made of a magnetic material with high magnetic permeability.

The electromagnetic driver 30 includes a yoke body 31 that is formed in a cylindrical shape and has one end that also serves as a bearing.
, an annular permanent magnet 33 attached to the inner peripheral surface of the other end of the yoke body 31, and a coil 34 wound in the circumferential direction around the inner peripheral surface of the permanent magnet 33. A Teflon-based resin coating layer 32 is applied to the sliding surface of the bearing portion of the yoke body 31. A certain clearance is formed between the inner circumference of the coil 34 and the circumferential surface of the guide shaft.

Next, the operation according to this embodiment will be explained.

As shown in FIG. 3, if the inner circumferential side of the permanent magnet 33 is the N pole and the outer circumferential side is the S pole, the permanent magnet 33 and
A magnetic closed loop is formed by the guide shaft 21 and the yoke body 31, and a magnetic field H is formed between the permanent magnet 33 and the guide shaft 21 in the direction from the permanent magnet 33 to the guide shaft 21. When a current A is passed through a coil 34 wound in a circumferential direction perpendicular to the magnetic field H, a force acts to move the coil 34 in a direction along the guide shaft 21 perpendicular to the direction in which the magnetic field H and the current A flow. . Then, the electromagnetic driver 30 is moved in the direction along the guide shaft 21, and the optical pickup main body 22 is moved along the guide shafts 20,21.

Next, by passing a current through the coil 34 in the opposite direction to the above-mentioned direction, the optical pickup main body is moved along the guide shafts 20, 21 in the opposite direction to the above-mentioned direction.

FIG. 4 shows another embodiment of the electromagnetic driver attached to the optical pickup main body 22 and mounted on the guide shaft 21.

The electromagnetic driver 40 has a shape in which an annular permanent magnet 43 is sandwiched between a yoke body 41 that also serves as a disk-shaped bearing and an annular yoke body 42 in the shape of a sandwich arch. Guide shaft 21 of yoke body 41
A resin coating layer 44 is formed on the sliding surface that slides to reduce the coefficient of friction as much as possible. A coil 45 is attached to the inner peripheral surface of the yoke body 42. The permanent magnet 43 has an S pole on the yoke body 41 side and an N pole on the yoke body 42 side. As a result, a magnetic closed loop is formed by the permanent magnet 43, the yoke body 42, the guide shaft 21, and the yoke body 41, and a magnetic field is formed between the yoke body 42 and the guide shaft 21. When a current is applied to the coil 45, the optical pickup main body is moved along the guide shafts 20, 21 as in the previous embodiment.

In the embodiment, the resin coating layer is formed on the sliding surface of the yoke body that also serves as a bearing, but the resin coating layer may be formed on the circumferential surface of the guide shaft.

In the embodiment, the electromagnetic driver is only provided at one location, but a plurality of electromagnetic drivers may be provided.

Effects of the Invention As explained above, according to the linear feeding device of the present invention, the driven body is guided and supported in the linear feeding direction by the shaft penetrating support structure, so that the movement is large in both directions along the guide shaft axial direction. It can be moved by a stroke, and a large operating stroke can be taken for linear feed.

Further, since a resin coating layer is formed on the sliding portion of the guide shaft and the electrode driver, smoother linear feeding operation is possible.

Furthermore, since the electromagnetic driver also serves as a bearing fitted to the guide shaft, the number of parts and the space occupied by the bearing system are reduced, and the device configuration can be made thinner and more compact.

By the way, if the linear feeder according to the present invention is applied to a linear feeder for an optical pickup, it is possible to perform tracking servo with much more precision than in a conventional feeder using a DC motor. Furthermore, the driven object is not limited to optical pickups, but can be widely applied as a linear feeding device for lightweight driven objects.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing a linear feed device according to the present invention, Fig. 2 is a perspective view of its main parts, Fig. 3 is a side sectional view showing its operation, and Fig. 4 is a side sectional view showing another embodiment. , FIG. 5 is a perspective view showing a conventional example. 20, 21... Guide shaft, 22... Optical pickup body (driven object), 23, 23, 24...
... Bearing, 30, 40 ... Electromagnetic driver, 31, 4
1, 42... Yoke body, 33, 43... Permanent magnet, 34, 45... Coil, 32, 44... Resin coating layer, H... Magnetic field, A... Current.

Claims (1)

[Claims for Utility Model Registration] 1. A device that supports a driven body through a horizontally arranged guide shaft via a plurality of bearings, and linearly feeds the driven body in both directions along the guide shaft. The guide shaft is formed of a material with high magnetic permeability, and at least one bearing fitted on the guide shaft is formed of an electromagnetic driver composed of a yoke body, a permanent magnet, and a coil, and the yoke body or the guide A linear feeder with a resin coating layer formed on either sliding surface of the shaft. 2. The linear feeding device according to claim 1, wherein the electromagnetic driver is formed so that a permanent magnet is sandwiched between a pair of yoke bodies.